I'm writing a Shiny app for visualizing insurance benefit plans at my company. Here is what I'd like to happen:
selectInput
or sliderInput
where the user will choose the number of individuals on their medical planHere's my current ui.R
file with hard coded inputs, simulating a family of four:
shinyUI(pageWithSidebar(
headerPanel("Side by side comparison"),
sidebarPanel(
selectInput(inputId = "class", label = "Choose plan type:",
list("Employee only" = "emp", "Employee and spouse" = "emp_spouse",
"Employee and child" = "emp_child", "Employee and family" = "emp_fam")),
sliderInput(inputId = "ind1", label = "Individual 1",
min = 0, max = 20000, value = c(0, 2500), step = 250),
sliderInput(inputId = "ind2", label = "Individual 2",
min = 0, max = 20000, value = c(0, 2500), step = 250),
sliderInput(inputId = "ind3", label = "Individual 3",
min = 0, max = 20000, value = c(0, 2500), step = 250),
sliderInput(inputId = "ind4", label = "Individual 4",
min = 0, max = 20000, value = c(0, 2500), step = 250)
),
mainPanel(
tabsetPanel(
tabPanel("Side by Side", plotOutput(outputId = "main_plot", width = "100%")),
tabPanel("Summary", tableOutput(outputId = "summary"))
)
)))
Here's what it looks like (the transparent end sections are the result of HSA contributions from two of the plans. I thought it was a nice way to show both the premiums and medical expenses while showing the impact of the company HSA contribution. Thus, you'd just compare the length of the solid colors).
I've seen examples like this where the UI input itself is fixed (in this case, one checkboxGroupInput
exists, but its contents are tailored based on the choice from another UI input), but I've not seen examples of tailoring the number (or, say, type) of input elements spawned as the result of another UI input's contents.
Any suggestions on this (is it even possible)?
My last resort will be to create, say, 15 input sliders and initialize them to zero. My code will work just fine, but I'd like to clean up the interface by not having to create that many sliders just for the occasional user who has a very large family.
Update based on Kevin Ushay's answer
I tried to go the server.R
route and have this:
shinyServer(function(input, output) {
output$sliders <- renderUI({
members <- as.integer(input$members) # default 2
max_pred <- as.integer(input$max_pred) # default 5000
lapply(1:members, function(i) {
sliderInput(inputId = paste0("ind", i), label = paste("Individual", i),
min = 0, max = max_pred, value = c(0, 500), step = 100)
})
})
})
Immediately afterwards, I try and extract the values out of input
for each individual's expenses:
expenses <- reactive({
members <- as.numeric(input$members)
mins <- sapply(1:members, function(i) {
as.numeric(input[[paste0("ind", i)]])[1]
})
maxs <- sapply(1:members, function(i) {
as.numeric(input[[paste0("ind", i)]])[2]
})
expenses <- as.data.frame(cbind(mins, maxs))
})
Lastly, I have two functions that create objects to store a data frame for plotting based on the low and high medical expense estimates. They're called best_case
and worst_case
and both need the expenses
object to work, so I call it as my first line as I learned from this question
best_case <- reactive({
expenses <- expenses()
...
)}
I got some errors, so I used browser()
to step through the expenses
bit and noticed peculiar things like input$ind1
not seeming to exist from within the expenses
function.
I also played around with various print()
statements in it to see what was happening. The most striking is when I do print(names(input))
as the very first line in the function:
[1] "class" "max_pred" "members"
[1] "class" "ind1" "ind2" "max_pred" "members"
I get two outputs, which I believe is due to the defining of expenses
and subsequent calling of it. Strangely... I don't get a third when worst_case
uses the exact same expenses <- expense()
line.
If I do something like print(expenses)
inside of my expenses
function, I also get duplicates:
# the first
mins maxs
1 NA NA
2 NA NA
# the second
mins maxs
1 0 500
2 0 500
Any tips on why my input
elements for ind1
and ind2
wouldn't show up until expenses
is called the second time and thus prevent the data frame from being created correctly?
You could handle generation of the UI element in server.R
, so you have something like:
ui.R
----
shinyUI( pageWithSideBar(
...
selectInput("numIndividuals", ...)
uiOutput("sliders"),
...
))
and
server.R
--------
shinyServer( function(input, output, session) {
output$sliders <- renderUI({
numIndividuals <- as.integer(input$numIndividuals)
lapply(1:numIndividuals, function(i) {
sliderInput(...)
})
})
})
When I have UI elements that depend on values from other UI elements, I find it easiest to generate them in server.R
.
It's useful to understand that all of the _Input
functions just generate HTML. When you want to generate that HTML dynamically it makes sense to move it to server.R
. And perhaps the other thing worth emphasizing is that it's okay to return a list
of HTML 'elements' in a renderUI
call.